安全距离是由（）、（）以及（）三种因素决定的。
参考答案：绝缘水平；带电作业时过电压水平；必须的安全裕度
. Only _____ in a foreign-funded enterprise ______ the importance of learning English well.
A．when I worked, I realized
B．when I worked, did I realize
C．when did I work, did I realize
D．when did I work, I realized
※ [7～10]. ( 3 )
A．
B．
C．
D．
